The present invention relates to display technology field, particularly to light guide plate and method and mold for manufacturing the same.
In the existing liquid crystal displays, a side-lit type backlight module 1, as shown in FIG. 1, comprises a back plate 10, a bottom reflection sheet 11, lattice points 12, a light guide plate 13, a light source 14, a diffusion plate 15, optical sheets 16 and a frame 17.
In the side-lit type backlight module 1, the light emitted by cold cathode fluorescent lamp or light emitting diode which serves as the light source 14 enters the light guide plate 13 from its sides. After passing through the light guide plate 13 and the reflected at the lattice points 12 on the bottom surface of the light guide plate, part of the incident light exits the top face of the light guide plate 13. The other part of the light gets to the surface of the bottom reflection sheet 11 after refraction, reflected on the bottom reflection sheet 11, back into the light guide plate 13 again, and exits the top face of the light guide plate 13. Meanwhile, the light exiting the top face of the light guide plate 13 is diffused and converged by sheets (any combination of the diffusion plate 15, the optical sheets 16 and protective sheets) disposed above the light guide plate 13, making optical pictures uniform and the center of the pictures sufficiently bright. The optical sheets generally are prism sheets and/or brightness enhancement sheets.
Because the raw material for a light guide plate used in liquid crystal display industry is mainly polymethyl methacrylate which has optical properties including: transmittivity of 92%, index of refraction of 1.49, and thus there is a 8% of light energy lost due to absorption by the light guide plate and the brightness of the picture will be decreased when a beam of light exits the light guide plate. However, the loss of light energy can be compensated only by adding an optical sheet having a gain of about 10% and this will increase the manufacturing cost and make the product less competitive.